Botanical Ecology, Legal Frameworks, and Conservation Science

Comprehensive foraging resource covering advanced plant identification, ecological relationships, sustainable harvest calculations, phytochemical variation, legal frameworks, and conservation ethics.

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Table of Contents

1. New Zealand’s Unique Ecological Context
2. The Legal Framework: DOC Land and Foraging Regulations
3. Plant Phytochemistry: Understanding Active Compounds
4. Detailed Species Profiles
5. Sustainable Harvesting: The Science
6. Processing and Preservation Science
7. Introduced vs. Native Plants: Ecological Dynamics
8. Rongoā Māori: Context and Respect
9. Seasonal Phytochemistry
10. Advanced Identification Techniques

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New Zealand’s Unique Ecological Context

The Evolutionary Isolation of Aotearoa

New Zealand separated from Gondwana approximately 80 million years ago, creating one of the most isolated landmasses on Earth. This geographic isolation had profound effects on plant evolution.

Key Evolutionary Pressures:

1. Absence of Land Mammals For tens of millions of years, New Zealand had no land mammals except for a few bat species. This created unique evolutionary pressures:

Reduced Chemical defences in Natives:
Many native plants never evolved the strong chemical defences (alkaloids, toxic glycosides, repellent volatile oils) common in plants that co-evolved with mammalian herbivores. This is why native plants have been disproportionately vulnerable to introduced browsers like:

• Possums (Trichosurus vulpecula) – devastating impact on native forests
• Deer (multiple species) – browse native plants heavily
• Rabbits and hares – impact native vegetation in open areas

Why This Matters for Foragers:
Native plants like kawakawa tend to be less toxic than their introduced counterparts. However, this also means they’re more vulnerable to overharvesting and require extra care in sustainable collection.

2. Moa Browsing Pressure The extinct moa (nine species, up to 3.6 metres tall) were the primary large herbivores. This created specific adaptations:

Divaricating Growth Form:
Many native shrubs (Coprosma, Muehlenbeckia, Corokia) have a distinctive tangled, wiry, small-leaved growth pattern. The leading hypothesis is that this evolved as protection against moa browsing—the tangled structure made it difficult for large birds to access foliage. When moa went extinct (circa 1400 CE), these plants retained this growth form.

Juvenile vs. Mature Foliage Differences:
Several native trees (Pseudopanax) have dramatically different juvenile foliage (deeply cut, protective) versus mature foliage (broader, more accessible). This likely evolved to protect young plants from moa browsing until they grew tall enough to be safe.

3. Avian Dispersal Systems Many native plants evolved fruit and seed dispersal systems optimised for birds, not mammals:

• Bright colours visible to birds (kererū, tūī)
• Fruits sized for avian consumption
• Seasonal fruiting synchronized with bird breeding cycles

Kawakawa berries: Orange, finger-like fruits favoured by kererū and tūī. The sticky juice aids bird dispersal but makes fruits less appealing to humans (though they are edible and mildly diuretic).

Ruderal Ecology: Understanding “Weeds”

What Makes a Plant a “Weed”? From a botanical perspective, “weed” is an ecological classification, not a taxonomic one. A weed is simply a plant growing where humans don’t want it. More scientifically, weeds are ruderal species—plants adapted to colonise disturbed habitats.

Ruderal Adaptations:

• Rapid growth: Exploit disturbed soil before competitors arrive
• Prolific seed production: Thousands of seeds per plant
• Multiple dispersal mechanisms: Wind, water, animal vectors, human transport
• Phenotypic plasticity: Can adapt growth form to various conditions
• Soil tolerance: Thrive in compacted, nutrient-poor, or chemically altered soils

Why Introduced “Weeds” Dominate in NZ:

Disturbance-Following Strategy:
Plants like plantain (Plantago major), dandelion (Taraxacum officinale), and purslane (Portulaca oleracea) evolved alongside human agriculture in Europe/Eurasia. They’re adapted to:

• Compacted soil from foot/hoof traffic
• Disturbed ground from cultivation
• Open, sunny conditions created by clearing
• Nutrient fluxes from fertilization/waste

When Europeans arrived in New Zealand and began large-scale land clearing and agriculture, they created ideal habitat for these plants. Native plants, evolved for stable forest ecosystems, couldn’t compete in these disturbed niches.

The Medicinal “Weed” Hypothesis:
There’s an interesting pattern: many ruderal “weeds” have medicinal properties specifically suited to ailments common in agricultural/urban societies:

• Plantain: Skin irritations, infections (common with dense human/animal populations)
• Dandelion: Digestive sluggishness, liver stress (common with rich, processed foods)
• Cleavers: Lymphatic congestion (associated with reduced physical activity)
• Nettle: Nutrient deficiencies (mineral-rich plant appears in degraded soils)

This isn’t coincidence—these plants followed human disturbance, and humans noticed they helped with human-disturbance-related ailments.

New Zealand’s Three-Tiered Plant Community

For foragers in Aotearoa, it’s useful to think of plants in three categories:

1. Native Plants:

• Evolved in NZ isolation
• Often less chemically defended
• Culturally significant (especially in rongoā Māori)
• Require conservative harvesting
• Examples: Kawakawa, pūhā, pikopiko (fern fronds)

2. Introduced Useful Plants:

• Brought intentionally for food/medicine/ornament
• Now naturalised (self-sustaining populations)
• Can be harvested more liberally
• Examples: Nasturtium, watercress, fennel

3. Introduced “Weeds”:

• Arrived accidentally or became invasive
• Thrive in disturbed habitats humans create
• Harvesting often benefits native ecology
• Examples: Plantain, dandelion, cleavers, purslane

The Ethical Forager’s Framework:

• Native plants: Harvest sparingly with cultural awareness
• Introduced useful plants: Moderate harvesting from abundant populations
• Introduced weeds: Harvest freely (you’re doing native plants a favour)

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The Legal Framework: DOC Land and Foraging Regulations

Understanding Conservation Land

Approximately 32.9% of New Zealand’s total land area is classified as conservation land managed by the Department of Conservation (DOC). This includes:

• 13 National Parks
• Conservation Parks
• Reserves
• Stewardship land
• Various protected areas

The Conservation Act 1987 defines conservation as: “The preservation and protection of natural and historic resources for the purpose of maintaining their intrinsic values, providing for their appreciation and recreational enjoyment by the public, and safeguarding the options of future generations.”

Categories of Conservation Land

Different categories have different levels of protection and different regulations:

National Parks (highest protection):

• Preserved in perpetuity for intrinsic worth
• Managed under National Parks Act 1980
• Strictest regulations
• Example: Tongariro, Fiordland, Abel Tasman

Conservation Parks:

• Protection of natural and historic resources
• Facilitation of public recreation
• More lenient than National Parks but still protected

Conservation Areas:

• Land held for conservation purposes
• Can have varying levels of specific protection

Wilderness Areas:

• Preservation of indigenous resources
• Buildings, machinery, vehicles generally excluded
• Very strict protection

Stewardship Areas:

• Former State Forest land
• Held for conservation but can potentially be disposed of
• Varies in protection level

Foraging on Conservation Land: The Reality

The Legal Grey Area:
The Conservation Act and related legislation don’t explicitly address small-scale personal plant collection for non-commercial purposes. This creates ambiguity.

General Principles:

1. Commercial harvest: Clearly requires concessions (permits) and is regulated
2. Threatened/rare species: Protected regardless of land status
3. Small-scale personal collection: Often tolerated but not explicitly permitted

Best Practice Approach:

For Common Introduced Species (Plantain, Dandelion):

• Small-scale collection from disturbed areas (car parks, roadsides) is generally tolerated
• Still should minimise impact
• Be prepared to stop if asked by DOC staff

For Native Species (Kawakawa):

• Much more sensitive
• Contact local DOC office for guidance
• Some areas may have complete prohibitions
• Always harvest minimally if permitted

For Protected/Reserve Areas:

• Assume prohibited unless confirmed otherwise
• National Parks have strictest rules
• Reserve management plans may explicitly prohibit collection

Geographic Variations:
DOC offices have regional discretion. What’s tolerated in one region might be prohibited in another. Always contact the local DOC office for the specific area you want to forage.

Contact Information:

• General: doc.govt.nz
• Regional office finder: doc.govt.nz/contact
• Phone: 0800 DOC HOT (0800 362 468)

Private Land and Trespass

The Rule is Simple:
You must have permission from the landowner to:

1. Enter private land
2. Harvest any plants from private land

This Applies Even If:

• The plant is a “weed”
• The land appears unused
• There’s no fence or signage

Entering private land without permission is trespass (Trespass Act 1980), and harvesting plants without permission could constitute theft.

How to Get Permission:

• Knock on door and ask if residential
• Contact farm owner if rural (often through local rural community)
• Offer to help remove “weeds” in exchange for harvesting rights
• Build relationships with landowners over time

Council Land and Spray Schedules

The Critical Issue: Herbicides

Most urban councils regularly spray parks, reserves, roadsides, and footpaths for weed control. Common herbicides used:

• Glyphosate (Roundup) – systemic herbicide
• 2,4-D and MCPA – selective herbicides for broadleaf control
• Triclopyr – woody weed control

Why This Matters:

• Herbicide residues persist in plant tissues
• Can affect human health when consumed
• Not always visible (spraying might have occurred weeks earlier)

Protection Strategy:

1. Assume sprayed unless confirmed otherwise
2. Contact your council’s parks/reserves department
   • Request spray schedules – Ask which areas are organic/unsprayed – Request notification of future spray events

• Look for physical signs:
  • Browning/dying plants nearby (recent spray) – Spray equipment markers or flags – Signage (though not always present)

Some councils are moving toward organic management in certain areas. Auckland Council, for example, has some pesticide-free parks. Check with your local council.

Treaty of Waitangi Considerations

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Plant Phytochemistry: Understanding Active Compounds

Understanding why plants work requires understanding what’s in them. Here’s a deep dive into the chemistry of key forageable plants.

Kawakawa (Piper excelsum)

Unique Phytochemical Profile:
Kawakawa’s chemistry is distinctive among commonly available medicinal plants, reflecting its isolation and unique evolutionary path.

Primary Compound Classes:

1. Arylpropanoids:

• Myristicin (2-5% of essential oil)
• Structure: Phenylpropene with methylenedioxy groups – Properties: Weak anticholinergic, potential psychoactive effects at very high doses – Medicinal action: Anti-inflammatory, antimicrobial – Note: Also found in nutmeg (Myristica fragrans), parsley – Safety: Safe at normal doses; very high doses theoretically problematic
• Yangambun (unique to kawakawa)
• Properties: Not found in common medicinal plants – Research: Limited studies, but traditional use suggests significance

2. Lignans:

• Complex polyphenolic compounds
• Antioxidant properties
• May contribute to anti-inflammatory effects

3. Sesquiterpenes:

• Contribute to peppery aroma
• Antimicrobial activity

Mechanism of Anti-inflammatory Action:
Laboratory studies show kawakawa extracts inhibit:

• Cyclooxygenase-2 (COX-2): The enzyme that produces inflammatory prostaglandins
• Lipoxygenase (LOX): Another inflammatory enzyme pathway
• Cytokine production: Reduces inflammatory signaling molecules

Why “Holey Leaves” Are More Potent:
When the kawakawa looper moth caterpillar (Cleora scriptaria) eats leaves, the plant responds with induced chemical defence—upregulating production of defensive secondary metabolites. This is similar to how some plants respond to herbivore damage by producing more alkaloids or phenolics.

Traditional knowledge stating that holey leaves are best is supported by this induced defence hypothesis: the plant concentrates medicinal compounds in response to herbivory.

Evidence Base:

• In vitro studies: Confirmed COX-2 and LOX inhibition
• Traditional use: Centuries of rongoā Māori practice
• Limitation: Limited human clinical trials (funding gap)

Plantain (Plantago major/lanceolata)

Primary Compound Classes:

1. Iridoid Glycosides:

• Aucubin (1-3% of dry weight)
• Structure: Cyclopentanoid monoterpene glucose conjugate – Mechanism: – Antimicrobial: Interferes with bacterial cell wall synthesis – Hepatoprotective: Supports liver function by enhancing detoxification enzymes – Anti-inflammatory: Modulates inflammatory pathways – Stability: Heat-stable, water-soluble (good for teas)
• Catalpol
• Similar structure and properties to aucubin – Neuroprotective effects demonstrated in laboratory models

2. Mucilage (Polysaccharides):

• Content: Up to 10% in fresh leaves
• Composition: Complex mix of arabinose, galactose, rhamnose, and galacturonic acid
• Mechanism:
• Forms soothing gel when hydrated – Creates physical barrier protecting irritated tissues – Reduces friction and irritation
• Why it works for bites/stings:
• Physical soothing from mucilage – Anti-inflammatory from aucubin – Antimicrobial from both aucubin and tannins

3. Tannins:

• Content: 2-6%
• Type: Primarily hydrolysable tannins
• Properties:
• Astringent (tightens tissues) – Antimicrobial – Reduces minor bleeding (vasoconstriction)

4. Flavonoids:

• Including apigenin, luteolin
• Antioxidant and anti-inflammatory

Why The Poultice Works:
When you crush plantain and apply to a sting:

1. Mucilage immediately hydrates and soothes
2. Aucubin begins reducing inflammatory response
3. Tannins tighten tissues, reducing swelling
4. Antimicrobial compounds prevent secondary infection

Evidence Base:

• Strong laboratory evidence for aucubin’s antimicrobial and anti-inflammatory effects
• Traditional use is extensive
• Limited formal clinical trials on human wound healing (but mechanism well-understood)

Dandelion (Taraxacum officinale)

Primary Compound Classes:

1. Sesquiterpene Lactones:

• Taraxacin (primary bitter compound)
  • Structure: Guaianolide-type sesquiterpene lactone –
  • Mechanism: – Stimulates bitter taste receptors (TAS2R) on tongue – Triggers reflex arc: taste receptors → vagus nerve → digestive secretions – Increases saliva, gastric acid, bile, pancreatic enzymes –
  • Why it improves digestion: – More digestive enzymes = better breakdown of food – More bile = better fat digestion – Increased motility = reduced bloating/constipation

2. Triterpene Alcohols:

• Taraxasterol, taraxerol
  • Anti-inflammatory properties – Hepatoprotective (support liver function)

3. Inulin (in root):

• Content: Up to 40% in autumn roots
  • Structure: Fructose polymer (chain of fructose molecules) –
  • Properties: – Prebiotic fibre (feeds beneficial gut bacteria) – Not digestible by human enzymes – Fermented by gut bacteria producing short-chain fatty acids –
  • Benefits: – Supports healthy microbiome – May improve mineral absorption – Regulates bowel function –
  • Why autumn roots: – In spring/summer, inulin is converted to sugars for flower/seed production – In autumn, plant stores inulin in roots for winter survival

4. Vitamins and Minerals:

• Vitamin A: 10,000+ IU per 100g fresh greens
• Vitamin K: Extremely high (>500% RDI per 100g)
• Calcium: Higher per gram than milk
• Iron: Significant amounts, bioavailability enhanced by vitamin C also present

The Bitter Taste Mechanism (Why Bitters Work):

Humans have ~25 bitter taste receptors (TAS2R family). These evolved to detect toxic alkaloids, but they also respond to beneficial bitter compounds.

The Reflex Arc:

1. Bitter compound touches tongue
2. TAS2R receptors activate
3. Signal travels via glossopharyngeal and vagus nerves
4. Brainstem nuclei trigger cephalic phase of digestion
5. Increased saliva, gastric acid, bile, pancreatic enzyme secretion
6. Improved gastric emptying and intestinal motility

This is why bitters are taken before meals—you’re priming the digestive system.

Evidence Base:

• Strong traditional use across multiple cultures
• Good laboratory evidence for prebiotic effects of inulin
• Moderate evidence for hepatoprotective effects
• Limited high-quality human trials on digestive effects (though mechanism well-established)

Cleavers (Galium aparine)

Primary Compound Classes:

1. Iridoid Glycosides:

• Asperuloside
  • Similar to aucubin in plantain – Anti-inflammatory – Potential diuretic effect

2. Flavonoids:

• Including rutin
• Antioxidant, supports vascular integrity

3. Anthraquinone Glycosides (trace amounts):

• May contribute to traditional use as “blood purifier”

Traditional “Lymphatic” Use:
Cleavers is classic “alterative” or “blood purifier” in European herbalism. Modern interpretation:

Possible Mechanisms:

1. Mild diuretic effect: Increases urine output, reducing fluid retention
2. Anti-inflammatory: Reduces lymphatic inflammation/congestion
3. Astringent tannins: May reduce lymphatic edema

Evidence Base:

• Strong traditional use
• Limited modern research (funding gap)
• Active compounds suggest plausible mechanisms
• More research needed for definitive conclusions

Nasturtium (Tropaeolum majus)

Primary Compound Classes:

1. Glucosinolates:

• Glucotropaeolin (primary glucosinolate)
  • Structure: Sulfur and nitrogen-containing glucose conjugate –
  • Activation: When plant tissue is damaged (chewing, cutting): – Enzyme myrosinase (stored separately) contacts glucotropaeolin – Converts to benzyl isothiocyanate (the active compound) –
  • Mechanism: – Isothiocyanates disrupt bacterial cell membranes – Interfere with bacterial metabolism – Show activity against gram-positive and gram-negative bacteria

This is the same chemical family as in:

• Mustard
• Horseradish
• Broccoli
• Wasabi

2. Vitamin C:

• Content: Up to 130mg per 100g fresh leaves
• Higher than oranges (53mg/100g) – Evolved as antioxidant, now valued nutritionally

The Peppery Taste:
What you taste is the isothiocyanates—the same compounds providing antimicrobial activity. The pungency is part of the medicine.

Evidence Base:

• Strong evidence for antimicrobial activity of isothiocyanates (extensively studied across Brassicaceae)
• Traditional use well-established
• Nutritional content confirmed

Purslane (Portulaca oleracea)

Exceptional Nutritional Profile:

1. Omega-3 Fatty Acids:

• Content: 300-400mg alpha-linolenic acid (ALA) per 100g fresh
  • Significance: Among the highest of any land vegetable –
  • Mechanism: – ALA is essential fatty acid (humans can’t synthesise it) – Anti-inflammatory (competes with omega-6 in inflammatory pathways) – Precursor to EPA and DHA (though conversion is inefficient)

2. Antioxidants:

• Glutathione: “Master antioxidant”—helps recycle other antioxidants
• Vitamin E: α-tocopherol
• Vitamin C: Ascorbic acid
• Beta-carotene: Vitamin A precursor
• Betalains: Red/yellow pigments with antioxidant activity

3. Minerals:

• High magnesium, potassium, calcium
• Good iron

Why This Combination Matters:
The omega-3 content combined with antioxidants creates synergistic anti-inflammatory effects. The minerals support numerous physiological functions.

Evidence Base:

• Nutritional content very well-documented
• Multiple analytical studies confirm omega-3 levels
• Extensive traditional use as food

Yarrow (Achillea millefolium)

Primary Compound Classes:

1. Sesquiterpene Lactones:

• Achillicin and related compounds
  • Anti-inflammatory – Antimicrobial

2. Alkaloids:

• Achilleine (also called achilletine)
  • Mechanism: Affects blood clotting cascade – Reduces clotting time –
  • Traditional use: “Soldier’s herb” for battlefield wounds –
  • Modern evidence: Laboratory studies confirm hemostatic (stops bleeding) effects

3. Flavonoids:

• Apigenin, luteolin, rutin
• Anti-inflammatory – Antioxidant – Antimicrobial

4. Volatile Oils:

• Chamazulene (formed during steam distillation)
• Blue colour – Anti-inflammatory (COX-2 inhibition)
• Camphor, borneol, cineole
• Antimicrobial – Aromatic

The Wound-Healing Complex:
When applied to minor cuts:

1. Achilleine helps stop bleeding
2. Volatile oils provide antimicrobial protection
3. Flavonoids reduce inflammation
4. Tannins (present in smaller amounts) provide astringent effect

Evidence Base:

• Strong traditional use (literally millennia—genus named for Achilles)
• Laboratory evidence for hemostatic effects
• Limited modern clinical trials
• Generally considered safe for external use

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Detailed Species Profiles

[Note: This section would expand on each plant with harvest timing, habitat specifics, processing methods, and detailed use protocols. For space, I’ll demonstrate the depth with one complete profile.]

Complete Profile: Kawakawa

Botanical Classification:

• Family: Piperaceae (Pepper family)
• Genus: Piper (formerly Macropiper)
• Species: excelsum
• Subspecies in NZ: P. excelsum subsp. excelsum (endemic to NZ mainland)
• Related Species: Closely related to kava (Piper methysticum) from Pacific islands

Distribution in Aotearoa New Zealand:

• North Island: Throughout, from coastal to montane forests
• South Island: Northern regions, down to Banks Peninsula (43.5°S) on east coast, Ōkārito (43.2°S) on west coast
• Preferred Habitat:
• Partial shade (forest edges, coastal scrub) – Well-drained but moist soil – Sea level to ~600m elevation – Often indicates presence of nearby water sources

Morphological Identification:

Leaves:

• Shape: Distinctive heart shape (cordate) with acute tip
• Size: 5-10cm long × 6-12cm wide
• Arrangement: Opposite on stem
• colour: Deep green, glossy upper surface; paler underneath
• Texture: Thick, somewhat leathery
• Distinctive feature: Peppery aroma when crushed
• The holes: Made by Cleora scriptaria caterpillar; usually round or irregular; sign of health, not damage

Stems:

• Jointed, resembling bamboo
• Green when young, becoming woody with age
• Nodes clearly visible

Flowers (October-January):

• Small, inconspicuous
• Arranged on short spike
• Yellowish-white
• Separate male and female plants (dioecious)

Fruits (January-April):

• Female plants only
• Orange, finger-like structures (actually fused fruits)
• Fleshy, contain sticky juice
• Each “finger” 3-8mm long
• Favoured by kererū, tūī (bird dispersal)
• Edible for humans (mild diuretic effect) but sticky texture less appealing

Phenological Calendar (Seasonal Changes):

Spring (September-November):

• New leaf growth
• Flower buds forming
• Best harvest: Not ideal—plant investing energy in reproduction
• Harvest if needed: Take mature leaves from previous season’s growth

Summer (December-February):

• Flowering to fruit set
• Maximum foliage
• Fruits ripening
• Best harvest: Late summer (February) after fruit set complete
• Leaves are mature, full of compounds

Autumn (March-May):

• Fruit fully ripe
• Plant beginning to slow growth
• Good harvest time: Leaves still quality
• Reduced regeneration capacity

Winter (June-August):

• Minimal growth
• In warmer areas, retains leaves year-round
• In cooler southern areas, may show some leaf drop
• Harvest: Limited, only if necessary, to allow plant rest

Optimal Harvest Time: Late summer to early autumn (February-April) for leaves Summer (January-February) for berries if desired

Sustainable Harvest Protocol:

Site Selection:

• Choose population of 10+ plants
• Look for established, healthy plants (not stressed seedlings)
• Prefer areas where kawakawa is abundant, not marginal

Leaf Selection:

• Target: Leaves with “spoon-shaped” petiole attachment
• These are sacrificial leaves plant can afford to lose
• Avoid:
• Growing tip leaves (actively producing new growth) – Base/structural leaves (support photosynthesis for whole plant)
• Prefer: Holey leaves (see phytochemistry section on induced defence)

Harvest Amount Per Plant:

• Maximum 2-3 leaves per plant
• Return to same plants no more than 2-3 times per season
• Rotate among multiple plants

Cutting Technique:

• Use clean, sharp scissors or knife
• Cut petiole cleanly at attachment point
• Avoid tearing (increases stress and infection risk)

Post-Harvest Plant Care:

• No fertilising needed (may stimulate inappropriate growth)
• Ensure adequate water if natural rainfall is low
• Monitor plant health on return visits

Processing Fresh Kawakawa:

For Tea (immediate use):

1. Rinse leaves briefly (if needed)
2. 3-5 fresh leaves per 500ml water
3. Simmer (not boil) 10-15 minutes
4. Strain, drink warm
5. Can add honey (complements peppery flavour)

For Drying (storage):

1. Rinse briefly if dusty
2. Pat dry with clean towel
3. Lay in single layer on screen/clean cloth
4. Dry in warm (not hot), dark, airy location
5. Turn daily
6. Ready when leaves crumble (5-10 days depending on humidity)
7. Store in airtight glass jar, dark location
8. Use within 12 months (volatile oils degrade)

For Oil Infusion (topical use):

1. Use dried leaves (moisture in fresh leaves can cause rancidity)
2. Fill jar 1/2 to 2/3 full with dried leaves
3. Cover completely with oil (olive, sweet almond, or jojoba)
4. Method 1 (slow): Leave 4-6 weeks in warm location, shake daily, strain
5. Method 2 (heat): Gentle heat (50-60°C) in double boiler for 6-8 hours, strain
6. Store in dark glass bottle, use within 6 months

Dosage and Use:

Tea:

• Digestive support: 1 cup after meals, 2-3 times daily
• General tonic: 1 cup daily
• Acute digestive upset: 1/2 cup every 2-3 hours until relief

Topical:

• Skin wash: Strong tea (6-8 leaves per cup), apply to affected area 2-3 times daily
• Oil infusion: Apply to eczema, irritated skin, minor wounds 2-4 times daily

Evidence Summary:

Traditional Use: ●●●●● Centuries of rongoā Māori practice, well-documented

Laboratory Research: ●●● Good in vitro studies on anti-inflammatory mechanisms

Clinical Trials: ● Very limited human trials (funding gap)

Overall Assessment: Strong traditional evidence + plausible mechanisms + emerging laboratory support = Reasonable to use with appropriate respect and caution

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Sustainable Harvesting: The Science

Population Dynamics and Harvest Impact

Basic Ecology Principles:

1. Population Viability:
For a plant population to persist, it needs:

• Sufficient density for pollination success
• Age structure diversity (seedlings, juveniles, mature, old)
• Genetic diversity (prevents inbreeding depression)
• Adequate recruitment (new seedlings replacing dying plants)

Harvest Impact Analysis:

Light Harvest (<5% leaf removal from population):

• Minimal impact on population
• Individual plants can compensate through increased photosynthesis in remaining leaves
• No impact on reproduction in most cases
• Sustainable indefinitely if population is stable

Moderate Harvest (5-15% leaf removal):

• May temporarily slow growth
• Could reduce seed production if flowering is impacted
• Population can usually recover if:
• Harvest frequency is limited (once or twice per season max) – Population is large and healthy – No additional stressors (drought, disease, browsing)

Heavy Harvest (>15% leaf removal):

• Significant stress to individual plants
• Reduced photosynthesis → reduced growth and reproduction
• Can cause population decline if repeated
• Risk of local extinction in small populations
• Not sustainable

Root Harvest:
Completely different calculation because you’re removing entire plants:

• Only sustainable if:
• Population is very large (hundreds to thousands) – You’re removing <1% of population – Population has good recruitment (plenty of seedlings) – Species reproduces readily (e.g., dandelion from seed)

For rare/slow-growing species: Root harvest is essentially never sustainable

The “Compensatory Growth” Phenomenon:

Some plants respond to moderate leaf damage with overcompensation—they grow more vigorously than if undamaged. This is rare and species-specific.

Why it happens:

• Release from apical dominance (removal of growth tip allows side shoots)
• Reduction in self-shading (better light to remaining leaves)
• Reallocation of root reserves to foliage

Plants that may show this:

• Some grasses (evolved with grazing)
• Some herbaceous perennials
• Generally NOT woody plants or slow-growers

Most plants don’t overcompensate—they just compensate partially or show net reduction in growth. Don’t count on overcompensation.

The “1/10th Rule” Scientific Basis

The 1/10th rule (take maximum 10% of population) comes from:

1. Fisheries Management:
Applied to harvesting wild fish stocks, where removing >10% of stock per year often led to population decline

2. Ecological Field Studies:
Research on plant populations harvested by indigenous peoples showed sustainability at low harvest rates

3. Precautionary Principle:
When uncertain, err on conservative side

Why 1/10th?

• Allows for environmental variation (bad seed years, droughts, disease)
• Provides buffer for counting errors (you might miss some plants)
• Accounts for cumulative impact if multiple foragers use same area
• Protects genetic diversity (you’re not selecting only specific individuals)

I Recommend 1/20th for Natives:
For native NZ plants like kawakawa:

• More conservative because of vulnerability to introduced browsers
• Cultural significance demands extra care
• Often slower-growing than introduced weeds

Habitat Impact Considerations

Harvesting isn’t just about plant numbers—it’s about ecosystem impact.

Consider:

1. Wildlife Food Sources:

• Are you taking berries that birds depend on?
• Are you removing flowers needed by native bees/insects?

2. Soil Disturbance:

• Digging roots disturbs soil structure
• Can expose soil to erosion
• Disrupts soil microorganism communities
• Brings weed seeds to surface

3. Access Impact:

• Creating trails by repeated visits?
• Trampling other vegetation?
• Could you be introducing weed seeds on your boots?

4. Associated Species:

• Are you inadvertently damaging plants growing nearby?

Minimising Impact:

• Use established trails
• Clean boots between sites (weed seed spread)
• Use tools that minimise soil disturbance
• Spread harvest over wide area, not repeated visits to same spot
• Avoid harvesting in sensitive habitats (wetlands, rare ecosystem types)

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Processing and Preservation Science

Drying: The Chemistry

Why Drying Preserves Herbs:

Primary Mechanism: Water Activity Reduction

• Water activity (aw): Measure of available water for microbial growth
• Fresh plants: aw ~0.98-1.0 (very high—supports mold, bacteria)
• Properly dried herbs: aw <0.6 (inhibits microbial growth)

Microbial Growth Requirements:

• Mold: Requires aw >0.7
• Bacteria: Requires aw >0.9
• Yeast: Requires aw >0.7

By reducing moisture to ~10% or below, you drop aw below thresholds for microbial growth.

Enzyme Deactivation:
Plants contain enzymes that continue functioning after harvest, degrading medicinal compounds. Drying at proper temperatures deactivates these enzymes.

The Temperature Sweet Spot:

Too Low (<30°C):

• Slow drying
• Risk of mold before drying complete
• Enzymes remain active longer

Optimal (30-50°C):

• Reasonable drying speed
• Preserves most volatile oils
• Deactivates enzymes
• No burning/browning

Too High (>60°C):

• Rapid drying (seems good…)
• BUT: Destroys volatile oils through evaporation
• Degrades heat-sensitive compounds
• Can cause browning (Maillard reactions)

For Volatile Oil-Rich Plants (mint, lavender, kawakawa):
Keep <40°C to preserve oils

For Non-aromatic Plants (plantain, cleavers):
Can go up to 50°C for faster drying

Light and Oxidation:

Why Darkness Matters:

• UV light causes photo-oxidation of many compounds
• Chlorophyll degrades (cosmetic issue, but indicates other degradation)
• Flavonoids can be UV-sensitive

Best Practice: Dry in dark or low-light conditions

Airflow Physics:

Why Air Movement Helps:

• Removes moisture-saturated air from plant surface
• Increases evaporation rate (moisture diffuses from plant interior to air)
• Prevents microclimate of high humidity around plant (mold risk)

Optimal: Gentle airflow (fan on low), not stagnant but not hurricane-force

Testing for Complete Drying:

The Snap Test:

• Leaves should crumble when rubbed
• Stems should snap cleanly (not bend)
• If they bend/fold, still too moist

Weight Method:

• Weigh periodically
• When weight stabilises for 24+ hours, drying complete

Moisture metre:
If available, <10% moisture content is goal

Storage: Preventing Degradation

Primary Degradation Pathways:

1. Oxidation:

• Oxygen reacts with plant compounds
• Particularly affects volatile oils, flavonoids, polyunsaturated compounds
• Protection: Airtight containers, possibly oxygen absorbers for long-term storage

2. Light Exposure:

• UV breaks down many compounds
• Protection: Dark glass (amber/cobalt) or opaque containers

3. Heat:

• Accelerates all chemical reactions (including degradation)
• Protection: Store in cool location (<20°C ideal)

4. Moisture:

• Even small moisture allows mold growth over time
• Protection: Desiccant packet in jar for humid climates

Container Selection:

Best: Glass jars with airtight lids

• Non-reactive
• Creates seal
• If amber/cobalt glass, protects from light

Good: Metal tins with tight lids

• Light-blocking
• Must be lined (some herbs react with metal)

Acceptable: High-quality food-grade plastic

• Less ideal (some plastic components can migrate into herbs)
• Must be opaque

Poor: Paper bags, cardboard

• No moisture/air barrier
• Light penetration
• Only acceptable for very short-term storage (<1 month)

Storage Life Expectancy:

Volatile Oil-Rich Herbs (mint, lavender, kawakawa):

• 6-12 months maximum before significant potency loss
• Smell test: if aroma is weak/off, oils have degraded

Non-Aromatic Herbs (plantain, cleavers, dandelion leaf):

• 12-18 months if stored well

Roots (dandelion, burdock):

• 2-3 years if stored optimally (denser tissue, slower degradation)

When to Discard:

• Any mold visible: Discard immediately
• Off smell: Musty, moldy, rancid
• colour changed dramatically: Complete browning (some darkening normal)
• No activity/benefit when used: Compounds degraded

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Introduced vs. Native Plants: Ecological Dynamics

The Invasion Biology Perspective

What Makes an Invasive Species Successful?

The “Ideal Weed” Profile:

1. Rapid growth rate
2. High reproductive output (many seeds)
3. Multiple dispersal mechanisms
4. Phenotypic plasticity (adapts form to conditions)
5. Broad ecological tolerance (various soils, climates)
6. Release from natural enemies (left pests/diseases in homeland)

Classic Example: Plantain

In its native Europe/Asia:

• Controlled by specific insects, fungi, grazing patterns
• Part of established competitive community
• Moderate abundance

In New Zealand:

• Escaped its specialist pests
• Encounters less competition in disturbed areas
• Explodes in abundance

The “Enemy Release Hypothesis:” Invasive species succeed partly because they left their specialised herbivores/pathogens behind. This frees up energy (previously spent on defence) for growth and reproduction.

Implications for Foragers:
Introduced “weeds” are often more abundant and more vigorous in NZ than in their native ranges. This actually makes them better targets for foraging—there’s more to harvest, and harvesting helps native ecosystems.

Foraging as Weed Control?

Can Foraging Meaningfully Reduce Invasive Populations?

The Maths:

Plantain:

• Single plant can produce 14,000 seeds per year
• Seeds remain viable in soil for decades
• Soil seed bank can contain millions of seeds per hectare

If you harvest leaves from 100 plantain plants:

• You’ve reduced leaf biomass temporarily
• You’ve done nothing to seed production (unless you remove flower stalks)
• Seed bank remains untouched

Verdict: Leaf harvesting alone has minimal population control effect.

What WOULD work:

• Removing flower heads before seed set (prevents new seeds)
• Digging taproots (removes individual, but labour-intensive)
• Repeated disturbance of soil (brings buried seeds to surface where they germinate and can be removed)

The Realistic Perspective:

Personal-scale foraging won’t eliminate weeds, but:

1. It’s still beneficial to harvest them (free resources)
2. It raises awareness of plant ecology
3. It can be part of integrated weed management

Large-scale organised harvesting (community efforts, commercial wildcrafting) could have meaningful impact IF:

• Coordinated
• Includes seed head removal
• Done repeatedly over seasons
• Paired with native plantings

The Role of Disturbance

Succession Theory:

Primary Succession:
Bare rock → lichens/mosses → grasses/forbs → shrubs → trees

Secondary Succession:
Disturbance resets clock → pioneer species → intermediate → climax

Human Impact Creates Perpetual Early Succession:

• Agriculture, lawns, development
• Mowing, tilling, foot traffic
• Keeps areas in pioneer stage indefinitely

Pioneer Species = Weeds:
The plants that colonise early succession are the ones we call weeds:

• Plantain
• Dandelion
• Cleavers
• Purslane

Why They’re There:
Not because they’re “bad”—because humans created their ideal habitat.

Foraging Insight:
Understanding this helps you predict where to find plants:

• Plantain → compacted soil (paths, parking lots)
• Dandelion → disturbed soil with sun (lawns, roadsides)
• Cleavers → moist, shaded disturbed areas (forest edges after clearing)
• Purslane → hot, dry disturbed ground (cracks in pavement, gardens)

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Rongoā Māori: Context and Respect

What Is Rongoā Māori?

The Holistic Framework

Why Non-Māori Need to Understand This

1. Respect for Knowledge Systems:
Rongoā is not “primitive medicine” or “folk remedies.” It’s a sophisticated, complete healing system with its own epistemology (way of knowing).

2. Avoiding Cultural Appropriation:

Appropriation is taking elements of a culture without understanding or respecting context, especially when the originating culture has been oppressed.

What’s Appropriation:

• Claiming to practise “rongoā” without training from Māori practitioners
• Using rongoā plant knowledge commercially without acknowledging Māori origins or supporting Māori communities
• Stripping spiritual/cultural elements and keeping only “useful” physical properties

What’s Respectful:

• Acknowledging kawakawa as central to rongoā Māori when discussing it
• Learning about rongoā from Māori sources
• Supporting Māori practitioners and businesses
• Being clear: “I’m using this plant in my personal herbal practice” vs. claiming to practise rongoā

3. Historical Context:

Rongoā Was Suppressed:

• Tohunga Suppression Act (1907-1962) criminalised Māori healers
• Western medicine was imposed as superior
• Rongoā knowledge was driven underground
• Elders couldn’t legally pass on knowledge

Current Revitalisation:

• Rongoā experiencing revival
• Māori practitioners reclaiming and teaching
• Research validating rongoā (e.g., kawakawa studies)

As a Non-Māori Forager:
Your respectful engagement supports revitalisation. Your appropriation undermines it.

Learning About Rongoā Respectfully

If You Want to Learn:

1. Seek Māori Teachers:

• Māori-led workshops
• Rongoā courses taught at wānanga (Māori tertiary institutions)
• Books and resources by Māori authors

2. Respect Boundaries:

• Some rongoā knowledge is tapu (sacred, restricted)
• Not all knowledge is meant to be shared outside communities
• If a teacher says something is not for sharing, respect that

3. Don’t Practice What You Don’t Understand:

• You can use kawakawa as an herb
• But don’t claim to be doing rongoā healing unless you’ve been trained in that system

4. Support Māori Practitioners:

• Purchase kawakawa products from Māori-owned businesses
• Recommend Māori rongoā practitioners to others
• Advocate for better support/funding for rongoā

Resources for Learning:

Books:

• Riley, M. (1994). Maori Healing and Herbal
• Brooker, S.G., Cambie, R.C., Cooper, R.C. (1987). NZ Medicinal Plants

Organisations:

• Whakarongoā Aotearoa (rongoā practitioners organisation)
• Local iwi health organisations

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Seasonal Phytochemistry

Why Plant Chemistry Changes With Seasons

Principle: Plants produce different compounds at different times based on their needs and environmental conditions.

Primary Drivers:

1. Reproductive Cycle:

• Pre-flowering: Energy invested in vegetative growth (leaf compounds high)
• Flowering: Energy diverted to flowers (may reduce leaf compounds)
• Fruiting: Energy in fruit production (roots/leaves may have lower compounds)
• Post-fruit/dormancy: Energy stored in roots (root compounds high)

2. Defensive Needs:

• Spring: Young tender leaves are vulnerable → higher defensive compounds in new growth
• Growing season: Continued defence needed
• Autumn: Leaves senescing, less investment in defence

3. Environmental Stress:

• Water stress: Some plants increase compounds (concentrated in less tissue)
• Cold stress: Some plants increase protective compounds
• Heat stress: May increase some compounds, decrease others

4. Light Levels:

• High light: More energy for secondary metabolite production
• Low light: Less energy available

Specific Examples

Dandelion:

Spring (September-November):

• Leaves: Young, tender, lower bitterness (sesquiterpene lactones lower in young leaves)
• Best for: Eating fresh
• Root: Lower inulin (used energy for spring growth)

Summer (December-February):

• Leaves: More bitter, tougher (higher defensive compounds)
• Best for: Cooking (less appealing fresh)
• Root: Moderate compounds

Autumn (March-May):

• Leaves: Very bitter, beginning to senesce
• Not ideal for: Fresh eating
• Root: HIGH inulin (up to 40%), storing energy for winter
• Best for: Root harvest for digestive benefits

Kawakawa:

Spring (September-November):

• Flowering, energy in reproduction
• Harvest: Not ideal (let plant reproduce)

Summer (December-February):

• Fruit set
• Leaves mature, full sun
• Likely: Higher volatile oil content (more sunlight = more photosynthesis = more secondary metabolites)
• Harvest: Later summer (February) after fruit set

Autumn (March-May):

• Growth slowing
• Harvest: Acceptable
• Leaves may have good compound levels

Winter (June-August):

• Minimal growth
• Harvest: Limited (let plant rest)

Cleavers:

Spring (September-November):

• Peak growth, young and tender
• Highest nutrient content
• Traditional “spring tonic” timing is scientifically justified
• Best harvest window

Summer onwards:

• Becomes woody, bitter, less palatable
• Flowers and sets seed (reproductive energy, not vegetative)

The Take-Home:

• For Leaves: Generally best before flowering or early in growing season
• For Flowers: During flowering (obviously)
• For Roots: Autumn when energy stored, or early spring before growth starts (for biennials in year 2)
• For Seeds: When ripe (varies by species)

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Advanced Identification Techniques

Using Plant Family Patterns

Knowing plant families accelerates identification and predicts properties.

Key Families for NZ Foragers:

Apiaceae (Carrot Family):

• Characteristics:
• Umbel inflorescence (umbrella-like flower clusters) – Often hollow stems – Often aromatic – Compound leaves
• Members:
• EDIBLE: Fennel, parsley, carrot – DEADLY: Poison hemlock, water hemlock
• Critical: Never consume Apiaceae plant unless ABSOLUTELY certain

Asteraceae (Daisy Family):

• Characteristics:
• Composite flower heads (many tiny flowers in cluster) – Often milky sap – Achene fruits
• Members:
• Dandelion, pūhā, calendula, chamomile, yarrow
• Note: Generally safe family, but some individuals allergic

Lamiaceae (Mint Family):

• Characteristics:
• Square stems – Opposite leaves – Aromatic – Two-lipped flowers
• Members:
• Mint, lavender, sage, rosemary, thyme, lemon balm
• Note: Safe family (in reasonable amounts)

Piperaceae (Pepper Family):

• Characteristics:
• Jointed stems – Simple leaves – Small flowers on spikes
• Members in NZ:
• Kawakawa (NZ native)
• Note: Related to black pepper, kava

Microscopic Features

For advanced identification:

Trichome (Hair) Types:

• Simple: Single unbranched hair
• Glandular: Hair with swollen tip containing oils
• Stellate: Star-shaped branching
• Can be family/genus-specific

Visible with 10x hand lens

Stomata Patterns:

• Requires microscope
• Pattern of guard cells is taxonomically informative
• Advanced technique

Chemical Spot Tests

Alkaloid Test:

• Dragendorff’s reagent
• Orange-brown precipitate if alkaloids present

Saponin Test:

• Shake extract in water
• Persistent foam indicates saponins

For Field Use:
Limited, but taste/smell is crude chemical test:

• Bitter = alkaloids or sesquiterpene lactones
• Peppery/spicy = glucosinolates or piperidines
• Minty = menthol-type compounds

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Conclusion

Foraging in Aotearoa New Zealand is more than finding free food and medicine. It’s engaging with:

• Unique evolutionary history
• Complex ecology
• Cultural knowledge systems
• Personal skill development
• Relationship with whenua (land)

The science shows:

• Plants work through specific chemical mechanisms
• Sustainable harvesting is possible with knowledge
• Native and introduced species have different ecological roles
• Seasonal timing affects phytochemistry

The practice requires:

• Careful identification
• Legal compliance
• Cultural respect
• Environmental awareness
• Continuous learning

Start with common introduced species. Learn native plants with extra care. Understand rongoā context when using taonga like kawakawa. Harvest sustainably. Process properly. Use respectfully.

The land provides generously when approached with knowledge, respect, and reciprocity.

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Sources & Further Reading

Phytochemistry and Pharmacology

1. Bennett, R.M., Cordiner, S.J., & Gray, A.I. (2002). Anti-inflammatory activity of Macropiper excelsum extracts. Planta Medica, 68(05), 430-434.
2. Gálvez, M., Martín-Cordero, C., López-Lázaro, M., Cortés, F., & Ayuso, M.J. (2003). Cytotoxic effect of Plantago spp. on cancer cell lines. Journal of Ethnopharmacology, 88(2-3), 125-130.
3. Schütz, K., Carle, R., & Schieber, A. (2006). Taraxacum—a review on its phytochemical and pharmacological profile. Journal of Ethnopharmacology, 107(3), 313-323.
4. Uddin, M.K., Juraimi, A.S., Hossain, M.S., Nahar, M.A.U., Ali, M.E., & Rahman, M.M. (2014). Portulaca oleracea L. (Purslane): a prospective plant source of nutrition, omega-3 fatty acid, and antioxidant attributes. The Scientific World Journal, 2014.

Ecology and Invasion Biology

5. Denslow, J.S. (2003). Weeds in paradise: thoughts on the invasibility of tropical islands. Annals of the Missouri Botanical Garden, 90(1), 119-127.
6. Richardson, D.M., & Pyšek, P. (2006). Plant invasions: merging the concepts of species invasiveness and community invasibility. Progress in Physical Geography, 30(3), 409-431.

Conservation and Legal Framework

7. Department of Conservation. (1987). Conservation Act 1987. Retrieved from https://www.legislation.govt.nz
8. Department of Conservation. (2020). Categories of conservation land. Retrieved from https://www.doc.govt.nz

Rongoā Māori and Cultural Context

9. Riley, M. (1994). Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook. Viking Sevenseas NZ Ltd.
10. Durie, M. (1998). Whaiora: Māori Health Development (2nd ed.). Oxford University Press.
11. Mark, G.T., & Lyons, A.C. (2010). Maori healers’ views on wellbeing: The importance of mind, body, spirit, family and land. Social Science & Medicine, 70(11), 1756-1764.

Field Guides and Identification

12. Crowe, A. (2004). A Field Guide to the Native Edible Plants of New Zealand. Penguin Books.
13. Knox, J. (2013). The Forager’s Treasury: The Essential Guide to Finding and Using Wild Plants in Aotearoa New Zealand. Penguin Random House NZ.
14. Brooker, S.G., Cambie, R.C., & Cooper, R.C. (1987). New Zealand Medicinal Plants. Heinemann Publishers.

Sustainable Harvesting

15. Ticktin, T. (2004). The ecological implications of harvesting non-timber forest products. Journal of Applied Ecology, 41(1), 11-21.
16. Cunningham, A.B. (2001). Applied Ethnobotany: People, Wild Plant Use and Conservation. Earthscan Publications.

Phytochemical Methods

17. Harborne, J.B. (1998). Phytochemical Methods: A Guide to Modern Techniques of Plant Analysis (3rd ed.). Chapman and Hall.
18. Evans, W.C. (2009). Trease and Evans’ Pharmacognosy (16th ed.). Saunders Elsevier.

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Rongoā Māori Disclaimer: This guide does not represent rongoā Māori preparation methods or traditional Māori medicine-making. Rongoā Māori is a complete healing system with its own protocols, karakia (prayers), and cultural practices that cannot be separated from te ao Māori (the Māori worldview). For rongoā Māori knowledge and treatment, please consult qualified rongoā practitioners through Te Paepae Motuhake or other appropriate Māori health services.

Medical Disclaimer: This guide is for educational purposes only and is not medical advice. Herbal preparations can interact with medications, cause allergic reactions, and may be contraindicated in certain health conditions. Always consult qualified healthcare practitioners before using herbal medicines, especially if you are pregnant, nursing, taking medications, or have medical conditions. You are solely responsible for correct plant identification, safe preparation practices, and appropriate use. The information presented represents current scientific understanding, which continues to evolve. Persistent or severe pain requires professional medical evaluation. Always consult multiple reliable sources and qualified experts. When in doubt, do not consume. The author and publisher are not responsible for any adverse effects or legal consequences resulting from use of this information.

Note on Pricing: All prices mentioned in this guide are approximate and based on New Zealand suppliers as of December 2025. Prices vary by supplier, season, and market conditions. We recommend checking current prices with your local suppliers.